The present invention relates to a glass door merchandiser type of refrigerated display case. While reference is made herein to the use of glass doors since those are the types of doors most frequently utilized, other types of doors can be used within the scope of the present invention. In addition, the term refrigerated, in accordance with the present invention, is intended to incorporate both those cases maintained at a temperature either at or in excess of 32.degree. F., such as frozen food cases. While the present invention can be utilized with both types of display cases, it is of particular advantage with glass door freezer cases.
In the operation of conventional refrigerated display cases having an opening in either the top or front wall, during the defrost operation a flow of air through the air conduit can be maintained and possibly directed along a path for causing the defrost air to flow outside, and away from the display case. Such an air flow pattern is especially utilized in the ambient air defrost refrigerated display cases. During the defrost operation of refrigerated display cases which do not have any doors covering the access opening and utilize either an electric or gas defrost system, the hot air created in the air conduit containing the evaporator coils can be allowed to flow along the air conduit and out of the display case since the access opening is not blocked. In refrigerated display cases having glass doors, or any other type of doors, allowing for such an air flow of the hot air from inside of the conduit to pass along the air conduit can lead to undesirable and improper operation of the display case.
In the glass door refrigerated display cases, any air leaving the openings to the air conduit is not free to flow out of the case due to the presence of the door and hence would flow into the display section of the display case. During the defrost operation, the defrosting of the frost buildup on the evaporator coils will release moisture to the air flowing through the air conduit. The moisture in the defrost air if allowed to reach the display section of the display case will collect on the products stored within the display case. In addition, the warm air will raise the temperature of the products in the display case. Such accumulation of frost on the refrigerated products and increase in the temperature of such products is detrimental both to the storage of the products and the appearance of such products. This problem is especially predominant in freezer display cases where the frozen products are more susceptible to damage.
Several exemplary embodiments of glass door refrigerated display merchandisers are shown in U.S. Pat. Nos. 3,063,254 to Dickinson, et al., 3,091,942 to Dickinson, et al. and U.S. Pat. No. Re. 26,587 to Thompson. None of these patents, however, provide any mechanism for preventing the heat created during the defrost operation from passing through the conduit and entering the display section of the merchandiser.